标题： 某些二维超导体在零磁场下的手征电流 显示英文标题

标题： Chiral currents at zero magnetic field in some two-dimensional superconductors

摘要： 无须施加外部磁场的非互易临界电流最近在几种超导体中被观察到，以石墨烯、Kagome化合物和欠掺杂铜氧化物的各种形式出现。 这一现象的必要条件是通常的超电流必须伴随手性超电流，即具有霍尔电流的对称性；等价地，超流密度张量必须有手性分量。 这也需要破坏反演对称性。 该现象的条件被推导出来，发现其正常态必须破坏时间反演和手性，而超导态还必须是非幺正的。 在观察到自发非互易临界电流的每种超导体中，都显示出正常态中存在这种对称性破缺的一些证据。 这类材料的超导态具有拓扑边缘电流，但其投影的电磁部分通常不是整数。 由于存在能隙，边缘态在超导体中受到保护。 在理想条件下，正常态应表现出反常霍尔效应。 显示英文摘要

摘要： Non-reciprocal critical currents without applying an external magnetic field have been observed recently in several superconductors, in various forms of Graphene, a Kagome compound and in an under-doped cuprate. A necessary requirement for this is that the usual supercurrent be accompanied by a chiral super-current, i.e. with the symmetry of a hall current; equivalently that the superfluid density tensor have a chiral component. It also requires inversion breaking. The conditions for this phenomena are derived to find that their normal states must break time-reversal and chirality and that the superconducting states must in addition be non-unitary. Each of the superconductors where spontaneous non-reciprocal critical currents are observed have shown some evidence for such broken symmetries in the normal state. The superconducting state of such materials have topological edge currents, but their projected electro-magnetic part is in general not an integer. The edge states are protected in the superconductor due to a gap. Under ideal conditions, the normal state should show an anomalous Hall effect.